Do you prefer a wide or standard aspect ratio display?

If standard, there are the Panasonic Toughbook W series and Fujitsu P7230.

There are many widescreen options: Sony TZ, Toshiba Protege R500, the upcoming ThinkPad X300, etc.

If you get Vista Business or Ultimate from the OEM, you are entitled to XP downgrade right. You can request the media from the system builder. This way you can try Vista to see you like it, and downgrade to XP if you don't.

Vista Business license is priced the same as XP Pro License, so it's better to go this way.